Migrate keycloak from v24.x to v25.x

[TechGardenCode]

Summary

Bitnami keycloak helm chart needs to be migrated from v24.9.0 to v25.x. Bitnami major bumps frequently include breaking changes (image restructuring, value key renames).

Current state

• Chart version: 24.9.0 (just updated from 24.7.7)
• Deployed in: 1276-dev, 1276-prod
• Renovate is configured to pin keycloak below v25 until migration is planned

Tasks

• Review Bitnami keycloak v25 changelog for breaking changes
• Test upgrade in 1276-dev first
• Verify SSO (sso.techgarden.gg) functionality post-upgrade
• Verify PostgreSQL compatibility
• Roll out to 1276-prod
• Update Renovate allowedVersions constraint